The present invention relates to an array structure and method of manufacturing the same, a charged particle beam exposure apparatus, and a device manufacturing method and, more particularly, to an array structure which can suitably be used as a blanking aperture array of a charged particle beam exposure apparatus, a method of manufacturing the array structure, a charged particle beam exposure apparatus having the array structure as a blanking aperture array, and a device manufacturing method using the charged particle beam exposure apparatus.
A multiple charged particle beam exposure apparatus using a plurality of charged particle beams employs a method of individually controlling irradiation of the plurality of charged particle beams using a blanking aperture array having a plurality of openings (e.g., Utility Model Publication No. 56-19402).
Generally, a blanking aperture array is manufactured by two-dimensionally forming a plurality of openings in a semiconductor crystal substrate made of, e.g., silicon at a predetermined interval and forming a pair of blanking electrodes on both sides of each opening. When voltage application/non-application to each pair of blanking electrodes is controlled in accordance with pattern data, a desired pattern can be formed on a sample.
For example, when one of the pair of blanking electrodes formed in correspondence with each opening is grounded, and a predetermined voltage is applied to the other blanking electrode, an electron beam passing through the opening is deflected. Since the electron beam passes through a lens arranged on the lower side and is then shielded by a single-opening aperture, the beam does not reach the sample surface (a resist layer on the semiconductor substrate). On the other hand, if no voltage is applied to the other electrode, the electron beam passing through the opening is not deflected. Hence, the electron beam passes through the lens arranged on the lower side and reaches the sample surface without being shielded by the single-opening aperture.
The blanking electrode of the blanking aperture array is typically made of a metal. A conventional blanking electrode forming method will be described with reference to FIGS. 19A and 19B. FIG. 19A shows only one of a plurality of pairs of blanking electrodes. FIG. 19B shows only one of the pair of blanking electrodes. First, as shown in FIG. 19A, a pair of trenches are formed in a substrate 41. An insulating film 42 is formed to cover the trench surfaces and substrate surface. A metal (e.g., tungsten) is deposited in the trenches by vapor deposition or sputtering to form a pair of metal electrodes 43. The substrate portion between the pair of metal electrodes 43 is removed by etching to form an opening. The insulating films on side surfaces of the opening are removed by etching.
In the conventional metal electrode forming method, since the depth of the trench is large relative to its width. Hence, as shown in FIG. 19B, in forming the insulating film 42 on the trench surface, the insulating film 42 may not uniformly be formed on the trench surface. In this case, the uncovered substrate 41 may electrically short-circuit to the metal electrode 43.
If the substrate 41 and metal electrode 43 electrically short-circuit, no predetermined voltage can be applied to the metal electrode 43. Accordingly, since the electron beam cannot appropriately be deflected, no desired pattern can be formed on a sample.
Additionally, even when the substrate 41 and metal electrode 43 do not short-circuit yet in manufacturing, they may short-circuit during use of the exposure apparatus due to, e.g., degradation at the thin portion of the insulating film 42.
Furthermore, in the conventional blanking electrode forming method, when the metal is deposited in the trench (the trench is filled with the metal), a void (cavity) is formed at the center of the trench, as shown in FIGS. 5A and 5B. It is therefore difficult to completely fill the trench.
More specifically, in the conventional forming method, a trench is formed in, e.g., a silicon substrate 51 by selective etching (trench etching). An SiO2 insulating film 52 is formed on the entire surface of the substrate 51, including the trench. Tungsten 53 as a prospective blanking electrode is deposited by sputtering. At this time, since the entire underlying layer of the tungsten 53 is made of the insulating film 52, the trench cannot be filled with the metal using selective growth, and a void 54 may be formed, as shown in FIG. 5B.
With such a void formed in a blanking electrode, when an opening is formed between a pair of blanking electrodes, and the insulating films 52 on the side surfaces of the opening are removed, the blanking electrode may partially break. Even when the blanking electrode does not break during manufacturing the blanking aperture array, the blanking electrode may be deformed by heat applied to it during use of the exposure apparatus having the blanking aperture array. The interval between the pair of blanking electrodes may vary accordingly. In this case, the electron beam cannot appropriately be deflected, and no desired pattern can be formed on a sample.
That is, in the conventional manufacturing method, it is difficult to manufacture a reliable blanking aperture array at a high yield.
The present invention has been made in consideration of the above situation, and has as its object to provide a highly reliable array structure such as a blanking aperture array, a method of manufacturing such an array structure at a high yield, a charged particle beam exposure apparatus having such an array structure, and a device manufacturing method using such a charged particle beam exposure apparatus.
According to the first aspect of the present invention, there is provided a method of manufacturing an array structure having a plurality of openings and a plurality of pairs of opposing electrodes which are arranged in correspondence with each of the plurality of openings to control loci of a plurality of charged particle beams that pass through the plurality of openings, respectively. The manufacturing method is characterized by comprising a trench formation step of forming a plurality of pairs of opposing trenches in a substrate, a side-surface insulating layer formation step of forming an insulating layer on a side surface of each of the plurality of pairs of opposing trenches, a process step of processing the plurality of pairs of trenches to expose a conductive layer to a bottom portion of each of the plurality of pairs of opposing trenches, an electrode formation step of selectively growing a conductive material on the conductive layer exposed to the bottom portion of each of the plurality of pairs of trenches to fill the plurality of pairs of trenches with the conductive material, thereby forming a plurality of pairs of opposing electrodes, and an opening formation step of forming an opening between each of the pairs of opposing electrodes.
According to a preferred embodiment of the present invention, in the electrode formation step, the conductive material is preferably grown in the plurality of pairs of opposing trenches by plating using, as a plating electrode, the conductive layer exposed to the bottom portion of each of the plurality of pairs of opposing trenches.
When one of two surfaces of the substrate, where formation of the plurality of pairs of opposing trenches starts in the trench formation step, is defined as an upper surface side, the manufacturing method preferably further comprises a lower-surface-side insulating layer formation step of, before the trench formation step, forming an insulating layer on a lower surface side of the substrate, and a conductive layer formation step of, after the lower-surface-side insulating layer formation step before the process step, forming the conductive layer on the insulating layer on the lower surface side of the substrate.
Alternatively, the manufacturing method preferably further comprises a lower-surface-side first insulating layer formation step of, before the trench formation step, forming a first insulating layer on a lower surface side of the substrate while defining, as an upper surface side, one of two surfaces of the substrate, where formation of the plurality of pairs of opposing trenches starts in the trench formation step, a conductive layer formation step of, after the lower-surface-side first insulating layer formation step before the process step, forming the conductive layer on the insulating layer on the lower surface side of the substrate, and a lower-surface-side second insulating layer formation step of, after the conductive layer formation step before the electrode formation step, forming a second insulating layer on, of exposing surfaces of the conductive layer, a surface opposite to the plurality of pairs of opposing trenches.
According to a preferred embodiment of the present invention, in the process step, the conductive layer is preferably exposed to the bottom portion by selectively etching an insulating layer at the bottom portion of each of the plurality of pairs of opposing trenches while leaving the insulating layer having a sufficient thickness formed on the side surface of each of the plurality of pairs of opposing trenches.
The manufacturing method may further comprise an interconnection layer formation step of forming an interconnection layer to be electrically connected to the plurality of pairs of opposing electrodes. In the interconnection layer formation step, the interconnection layer may be formed on a side of one of two surfaces of the substrate, where formation of the plurality of pairs of opposing trenches starts in the trench formation step, or on an opposite side. In the interconnection layer formation step, the interconnection layer which can individually control a potential difference to be applied to each of the plurality of pairs of opposing electrodes can be formed.
According to a preferred embodiment of the present invention, in the trench formation step, the plurality of pairs of opposing trenches preferably are so formed as to cause the plurality of pairs of opposing electrodes formed by filling the plurality of pairs of opposing trenches with the conductive material to shield the plurality of charged particle beams from insulating layers outside the plurality of pairs of opposing electrodes.
According to the second aspect of the present invention, there is provided a charged particle beam exposure apparatus which forms a pattern on a wafer using a plurality of charged particle beams, characterized by comprising a beam source which generates a plurality of charged particle beams, and a blanking aperture array which controls loci of the plurality of charged particle beams generated by the beam source to individually control whether the wafer is to be irradiated with the plurality of charged particle beams, wherein the blanking aperture array is an array structure manufactured by the above manufacturing method.
According to the third aspect of the present invention, there is provided a device manufacturing method of manufacturing a device through a lithography step, characterized in that the lithography step comprises a step of forming a pattern on a wafer using the above charged particle beam exposure apparatus.
According to the fourth aspect of the present invention, there is provided a method of manufacturing an array structure having a plurality of openings and a plurality of pairs of opposing electrodes which are arranged in correspondence with each of the plurality of openings to control loci of a plurality of charged particle beams that pass through the plurality of openings, respectively. The manufacturing method is characterized by comprising a first trench formation step of forming a plurality of pairs of opposing first trenches in a substrate, an insulating layer formation step of filling the opposing first trenches with an insulating material to form a plurality of pairs of opposing insulating layers, a second trench formation step of forming a plurality of pairs of opposing second trenches to be arranged inside the plurality of pairs of opposing insulating layers, an electrode formation step of filling the opposing second trenches with a conductive material to form a plurality of pairs of opposing electrodes, and an opening formation step of forming an opening between each of the pairs of opposing electrodes.
According to a preferred embodiment of the present invention, the manufacturing method may further comprise an interconnection layer formation step of forming an interconnection layer which applies a potential difference to the pairs of opposing electrodes. In the interconnection layer formation step, typically, the interconnection layer which can individually control the potential difference to be applied to each of the plurality of pairs of opposing electrodes can be formed. For example, preferably, the interconnection layer formation step is executed before the second trench formation step, and in the second trench formation step, the plurality of pairs of opposing second trenches are formed to communicate with the interconnection layer formed in the interconnection layer formation step.
According to a preferred embodiment of the present invention, in the electrode formation step, for example, the plurality of pairs of opposing second trenches are filled with the conductive material by plating using, as a plating electrode, the interconnection layer exposed to the bottom portion of each of the plurality of pairs of opposing second trenches after the second trench formation step.
According to a preferred embodiment of the present invention, in the insulating layer formation step, for example, the plurality of pairs of opposing first trenches are filled with silicon oxide as the insulating material formed using TEOS.
According to a preferred embodiment of the present invention, the manufacturing method further comprises a step of forming an insulating layer on a lower surface of the substrate, and in the first trench formation step, the plurality of pairs of opposing first trenches are formed by etching a predetermined portion of the substrate using the insulating layer formed on the lower surface of the substrate as an etching stopper.
According to a preferred embodiment of the present invention, in the second trench formation step, the plurality of pairs of opposing second trenches are so formed as to cause the plurality of pairs of opposing electrodes formed by filling the plurality of pairs of opposing second trenches with the conductive material to shield the plurality of charged particle beams from the plurality of pairs of opposing insulating layers.
According to the fifth aspect of the present invention, there is provided an array structure having a plurality of openings formed in a substrate and a plurality of pairs of opposing electrodes which are arranged in correspondence with each of the plurality of openings to control loci of a plurality of charged particle beams that pass through the plurality of openings, respectively, characterized in that each of the opposing electrodes is supported by the substrate through an insulating layer and arranged to shield a charged particle beam that passes between the opposing electrodes from the insulating layer.
The plurality of pairs of opposing electrodes can be formed by, e.g., plating. The insulating layer can be formed by forming a trench in the substrate and then filling the trench with an insulating material. Filling of the insulating material can be done by depositing a silicon oxide film using TEOS.
According to the sixth aspect of the present invention, there is provided a charged particle beam exposure apparatus which forms a pattern on a wafer using a plurality of charged particle beams, characterized by comprising a beam source which generates a plurality of charged particle beams, and a blanking aperture array which controls loci of the plurality of charged particle beams generated by the beam source to individually control whether the wafer is to be irradiated with the plurality of charged particle beams, wherein the blanking aperture array is an array structure manufactured by the above manufacturing method.
According to the seventh aspect of the present invention, there is provided a charged particle beam exposure apparatus which forms a pattern on a wafer using a plurality of charged particle beams, characterized by comprising a beam source which generates a plurality of charged particle beams, and a blanking aperture array which controls loci of the plurality of charged particle beams generated by the beam source to individually control whether the wafer is to be irradiated with the plurality of charged particle beams, wherein the blanking aperture array is the above array structure.
According to the eighth aspect of the present invention, there is provided a device manufacturing method of manufacturing a device through a lithography step, characterized in that the lithography step comprises a step of forming a pattern on a wafer using the above charged particle beam exposure apparatus.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.